DRAM with command-differentiated storage of internally and externally sourced data

ABSTRACT

A memory device having a DRAM core and a register stores first data in the register before receiving first and second memory access commands via a command interface and before receiving second data via a data interface. The memory device responds to the first memory access command by writing the first data from the register to the DRAM core and responds to the second memory access command by writing the second data from the data interface to the DRAM core.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/540,437 filed Dec. 2, 2021, which is a continuation of U.S. patentapplication Ser. No. 16/735,303 filed Jan. 6, 2020 (now U.S. Pat. No.11,204,863), which is a continuation of U.S. patent application Ser. No.15/882,847 filed Jan. 29, 2018 (now U.S. Pat. No. 10,552,310), which isa continuation of U.S. patent application Ser. No. 15/497,126 filed Apr.25, 2017 (now U.S. Pat. No. 9,898,400), which is a continuation of U.S.patent application Ser. No. 14/637,369 filed Mar. 3, 2015 (now U.S. Pat.No. 9,658,953), which is a continuation of U.S. patent application Ser.No. 13/383,205 filed Jan. 9, 2012, which is a 35 U.S.C. § 371 U.S.National Stage of International Patent Application No. PCT/US2010/039095filed Jun. 17, 2010, which claims priority to U.S. Provisional PatentApplication No. 61/235,564, filed Aug. 20, 2009. Each of the foregoingpatent applications is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates generally to the field of data processing,and more particularly to data storage and manipulation within a dataprocessing system.

BACKGROUND

The ever-increasing gap between processor performance and memorybandwidth is reflected in the growing timing penalty incurred when aprocessor must fetch data from operating memory. While processor-stalls(awaiting data retrieval) and architectural remedies (e.g., cachememories) are costly enough in single-processor systems, such costs tendto be multiplied in multi-processor systems (including multi-coreprocessors), particularly where multiple processors or processor coresshare storage locations (e.g., memory). In that case, modification ofthe shared data by one of the processors generally requires coherencycontrol—interprocessor communication or other high-level coordinationsuch as “locks” or “semaphores” to exclude the other processors fromaccessing the potentially-stale shared data while the data-modifyingprocessor carries out the multiple steps required to fetch the shareddata from the operating memory, modify the data, and then write themodified data back to the operating memory. In general, any of theexcluded processors that requires access to the shared data must awaitnotification that the exclusive access is complete.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1A illustrates an embodiment of a data processing system capable ofcarrying out access-protected data modification operations, referred toherein as “atomic” memory operations;

FIGS. 1B-1F illustrate the flow of data in a number atomic memoryoperations supported by the atomic memory device and atomic memorycontroller of FIG. 1A;

FIGS. 1G and 1H illustrate the flow of data in a number simplex memoryoperations supported by the atomic memory device and atomic memorycontroller of FIG. 1A;

FIG. 2 illustrates an embodiment of an atomic memory device in greaterdetail;

FIG. 3 illustrates an embodiment of a modify logic circuit that may beused to implement the modify logic shown in FIG. 2 ;

FIG. 4 illustrates a table of operations that may be initiated andcontrolled by the modify controller of FIG. 3 ;

FIG. 5 illustrates a generalized and exemplary operation of an atomicmemory device in response to receipt of a memory access command; and

FIG. 6 is a timing diagram illustrating signal timing during anexemplary duplex operation within the atomic memory device of FIG. 3 .

DETAILED DESCRIPTION

Memory devices having circuitry to perform data modification operationswithin the time interval generally required for data access aredisclosed in various embodiments. In general, by hiding the datamodification operation under or within the memory access time, exclusiveaccess to the data is established by the memory access processes withinthe memory device itself, thus obviating costly and inefficientexclusivity control mechanisms within the processor(s), memorycontroller or other upstream circuitry. In several single integratedcircuit embodiments presented below, an input-output pipeline of anintegrated circuit memory device includes capability to performmulti-step operations and to write data back into the same or differentmemory cells; because these operations are performed by the input-outputpipeline (which generally can only be used by one requestor at a time),a lock can be effectively established without using complicated softwaremechanisms or multi-processor communications.

A hypothetical illustration is presented with an example of two users,each having a separate workstation and desiring to update a sharedfinancial account database having an entry of $100. Each user'sworkstation might read the entry in-question ($100), and each user mightdesire to update the account to add different increments (e.g., to add$20 in the case of the first user, and to add $50 in the case of thesecond user). The use of software locks in this situation would implyunavailability of the entry or of related processing to one user untilthe other user is finished; the failure to use locks might imply thatthe second user's access may read a stale entry ($100) and thenoverwrite that stale entry with an update (e.g., $150) of stale info,resulting in an incorrect entry (e.g., $150 overwriting the first user'sentry of $120 when the correct value should be $170).

FIG. 1A illustrates an embodiment of a data processing system 100capable of carrying out access-protected data modificationoperations—that is, data modification operations that are carried outconcurrently or coextensively with a memory access operation and thusprotected from undesired intervening access by timing restrictionsimposed by the memory access itself. Such compound memory operations(i.e., involving data retrieval from one or more memory cores as well aslogical, arithmetic, exchange or other operations with respect to theretrieved data) are referred to herein generally as “atomic” operationsas they are indivisible from the standpoint of competing memoryrequestors. Accordingly, as the atomic character of such compoundoperations is enforced (effected) by circuitry within individual memorydevices that populate the memory subsystem, and issuance of specialized“atomic” memory access commands (or requests or instructions) by amemory controller, such memory devices are referred to herein as“atomic” memory devices and the memory controller as an “atomic” memorycontroller. Thus, the memory subsystem of FIG. 1A includes an atomicmemory controller 101 that responds to memory access requests (issuedvia a host request path, “HostReq”) from one or more processors 102 orother host devices running one or more threads; each “atomic operation”is effected by issuing corresponding command and address information toone or more atomic memory devices 103 via command/address path 110(“C/A”). In the case of a host-write request, write data is output fromthe host processor 102 to the atomic memory controller 101 via a hostdata path (“HostData”) and then from the atomic memory controller 101 tothe atomic memory devices 103 via memory data path 112 (“Data”).Conversely, in the case of a host-read request, read data is output fromone or more of the atomic memory devices 103 to the atomic memorycontroller 101 via the memory data path 112, and then from the atomicmemory controller 101 to the requesting host 102 via the correspondinghost data path.

With regard to the memory subsystem topology, any number of atomicmemory devices 103 may be coupled to the atomic memory controller 101 inany combination of point-to-point and multi-drop signaling paths. In oneembodiment, for example, the atomic memory devices 103 are organizedinto one or more memory ranks (i.e., selected as a unit via one or morechip-select lines or other selection mechanisms) with each atomic memorydevice 103 of the memory rank being coupled to the atomic memorycontroller 101 via a common command/address path 110 and via respective(dedicated-per-memory-device) memory data paths 110. By thisarrangement, the memory devices of a given rank may be selected as aunit (e.g., via a shared chip-select line or other device selectionmechanism) to receive the same memory access command and memory address,and to respond to the common command/address by receiving or outputtingrespective portions of the overall data word (via dedicated memory datapaths) being transferred between the rank of atomic memory devices 103and the atomic memory controller 101. In alternative embodiments,separate command/address paths 110 may be provided to enable selectionof atomic memory devices either as a rank or individually (or insub-groups within a rank), and/or multiple atomic memory devices 103 maybe coupled to a memory data path 110 (or to each memory data path 110 insystem 100) in a multi-drop arrangement.

Still referring to FIG. 1A, each of the atomic memory devices 103includes core access circuitry 107 to enable access to a memory core 105formed by one or more arrays of storage cells. The storage arrays of thememory core 105 may be populated by virtually any type of storage cellsincluding for example and without limitation, volatile or non-volatilememory; for example, the storage cells may include static random accessmemory (static RAM or SRAM) cells, dynamic RAM (DRAM) cells,charge-trapping cells such NAND or NOR flash memory cells, phase-changememory cells, ferro-magnetic memory cells or any other storage celltechnology that permits storage and retrieval of digital data. Further,the memory core 105 may include various signal lines and circuitry toenable access to the underlying storage cells such as, for example andwithout limitation, word lines to enable access to address-selected rowsof storage cells, bit lines to convey data signals betweenword-line-selected storage cells and sense amplifiers or like circuitry,and sense amplifiers themselves for sensing (and/or latching) signalsoutput from the selected cells during data retrieval (read) operationsand for driving signals back to the selected cells during write orrefresh operations. For purposes of clarity and definitiveness, atomicmemory devices are presented in embodiments below as having a DRAM coreand occasionally referred to as atomic DRAMs. In all such embodiments,data storage technologies other than DRAM may be used in accordance withthe innovations and improvements disclosed herein, with commensuratechanges in the memory core 105, core access circuitry 107, atomic memorycontroller 101 and interconnection topology.

Continuing with the exemplary atomic memory device 103 shown in FIG. 1A,core access circuitry 107 includes control logic circuitry 109 coupledto receive command and address information via the command/address path110 (which may be formed by separate command and address paths, or by asingle signaling path that is time-multiplexed with command and addressinformation) and data input/output (I/O) circuitry 115 to manage datatransfer between the memory core 105 and the external data path (i.e.,memory data path 112). The control logic circuitry 109 (“control logic”for short) responds to incoming commands and addresses by controllingoperation of the memory core 105 (initiating row and column decodingoperations, sense operations, refresh operations, precharge operations,programming operations, erase operations, etc.) and also controllingoperation of the data I/O circuitry 115. In particular, the controllogic circuitry 109 may manage the timing of data reception duringmemory write operations (and atomic memory operations that involve datastorage), enabling the data I/O circuitry to begin data samplingincoming data (e.g., write data, swap data and/or operand data asdiscussed below) from the external data path at a predetermined timewith respect to registration of a corresponding memory command and tolatch the incoming data in one or more registers or buffers that form aninterface to the memory core 105. Similarly, control logic 109 maymanage the timing of data transmission during memory read operations,enabling the data I/O circuitry 115 to begin unloading read data fromthe memory core interface and outputting the read data onto the externaldata path at a predetermined time with respect to registration of amemory read command (or a command to perform an atomic operation thatreturns data to the host requestor). Though not specifically shown,various timing signals including clock and/or strobe signals (i.e.,signals that transition to indicate the presence of valid data) may bereceived or generated within the atomic memory device 103 and used tocoordinate data sampling, transmission operations as well as internaloperations within the control logic 109, data I/O circuitry 115 and/ormemory core.

In contrast to conventional memory devices, the atomic memory device 103includes circuitry to execute the above-described data modificationoperations concurrently with data retrieval. More specifically, thecontrol logic 109 includes circuitry that responds to atomic operationcommands (i.e., commands to execute specified atomic operations) as wellas non-atomic memory read and write commands (and row activationcommands, precharge commands, refresh commands, program commands, erasecommands, and so forth as necessary to manage the underlying memorytechnology). Further, as shown in FIG. 1A, the data I/O circuitry 115includes modify logic circuitry 117 (“modify logic” for short) to enablemodification and write-back of retrieved data as it is en route to itsexternal destination, if any. In one embodiment, for example, the modifylogic 117 is coupled between internal serial data lines 131, 133 used toconvey outgoing (read) and incoming (write) data between data I/Osampler and driver circuits (121 and 123, respectively) and the memorycore interface. As retrieved data is shifted bit by bit onto theoutgoing serial data line 133 (i.e., away from the memory core 105), theserial data bits may be received within and operated upon by the modifylogic 117 in accordance with a specified modify-operation 128 to producemodified data which is, in turn, shifted bit by bit onto the incomingserial data line 131 (i.e., toward the memory core) and thus writtenback to the memory core 105. Because the overall data modification andwrite-back time may be completely or at least substantially hidden underthe data retrieval time itself (e.g., within the column access time orcolumn access cycle time of a memory device), the inherent timingrestrictions imposed by the memory core technology serve to preventundesired access to the modified data prior to its storage within thememory core 105 (including storage within the sense amp bank of thememory core, if not within the more remote storage cells themselves) andthus ensure coherency without need for coherency mechanisms within thehost requestor or memory controller. That is to say, a data read andwrite (e.g., read-modify-write) operation performed in the memory deviceis performed within the input-output path in a manner that it (a) isperformed far more quickly than lock mechanisms (where a memory lock isestablished through software or hardware during processing by a remotecontroller) and (b) cannot be interfered with by another incomingoperation. Returning to the hypothetical illustration presented above,relating to a financial account entry, the memory device may employ asingle read-modify-write operation such that an operation to write anupdated value into memory (e.g., $120) can be performed in a singlecommand, such updates can never be commenced for data that is stale.

FIGS. 1B-1F illustrates the flow of data in a number atomic memoryoperations supported by the atomic memory device 103 and atomic memorycontroller 101 of FIG. 1A. Exemplary operations that can be performedinclude operations that combine a data access with one or more logicaloperations, for example, increment operations, decrement operations,inversion, shift and similar operations. Other operations may combinemultiple memory access operations, such as for example a swap operationwhere data in one memory location is swapped with data from anothermemory location or with data provided by a memory command.

Starting with FIG. 1B, in a read/modify operation, data is retrieved aspart of a memory read operation, modified within the modify logic 117 inaccordance with a modify-operation 128 (“op”) specified by the controllogic (and thus by the atomic command from the atomic memory controller)and written back to the memory core 105 in place of the retrieved data.

In FIG. 1C, a similar atomic operation is performed except that, insteadof a unary operation in which the read data constitutes the soleoperand, a binary (two-operand) operation is performed in accordancewith the specified modify-operation 128 using the read data as a primaryoperand and an internally or externally sourced data value (shown inFIG. 1C as “operand” 140) as the secondary operand. As discussed below,such a sourced operand may be a value previously retrieved from thememory core 105 and stored within an operand register, a value storedwithin an operand register as part of a memory-controller-instructedregister-write operation, a carry-bit from another memory device (e.g.,from an adjacent rank) or any other operand data source. Anexternally-sourced operand (e.g., a value to be loaded into an operand)may be provided, for example, via the external data path (i.e., memorydata path 112 of FIG. 1A) in generally the same manner (though notnecessarily the same command-relative timing) as write data.Alternatively, an externally-sourced operand may be provided via thecommand/address path (e.g., time-multiplexed with other informationtransmitted thereon) or any other signaling connection to the atomicmemory device (e.g., an out-of-band transmission channel such as commonmode signaling over a differential data link, low-speed signal channelused to initialize the memory system, etc.). As a specific example of anexternally-sourced operand, an operand-load instruction and operandvalue may be provided from atomic memory controller 101 to atomic memorydevice 103 via the C/A and data paths, respectively (or via either pathindividually, or via any other in-band or out-of-band signaling path).The control logic 109 within the atomic memory device 103 responds tothe operand-load instruction by enabling the specified operand registerto be loaded with the incoming operand value. In addition to thetechniques identified above, a carry-bit or other operand or result ofan operation within modify logic 117 may be output from a memory device(or rank) as shown at 141 (“op result”) and provided to another memorydevice or to a memory controller, to indicate overflow/underflow orother results of such operations.

FIG. 1D illustrates an atomic data-exchange or data-swap operation thatmay be performed within the memory device architecture of FIG. 1A.Although similar to the binary operation shown in FIG. 1C, instead ofperforming a modification of the read data value, the read data isconditionally or unconditionally swapped with a swap data value (“swapdata”) via multiplexing circuitry 151. That is, the swap data value isconditionally or unconditionally written back to the memory core 105 inplace of the read data, and the swap data may also be conditionally orunconditionally returned to the memory controller (and thus the hostrequestor) to signify the swap result. As with the secondary operand ina binary operation, the swap data value may be internally or externallysourced (i.e., provided by a source within or outside the atomic memorydevice, respectively). In an unconditional swap, referred to hereinsimply as a swap operation, the swap data value is written back to thememory core in place of the read data value (i.e., overwriting the readdata value) while the read data value is returned to the memorycontroller (and thus to the host requestor). In a conditional swap,modify logic 117 evaluates the read data and/or swap data andconditionally exchanges (swaps) the read data and swap data depending onthe evaluation result. As an example, in a particular form ofconditional swap referred to herein as a compare-and-swap, the modifylogic compares the swap data and read data to determine which is moresuperlative (greater than, less than, higher magnitude, more ‘1’ or more‘0’ bits, etc.), writing the swap data back to memory core 105 only ifit is the more superlative value. Alternatively (or in response to adifferent type of conditional swap command), the read data alone or theswap data alone may be evaluated (or may be evaluated with respect to aregister-sourced condition or compare value as shown by dashed arrow 142in FIG. 1D) to determine whether the exchange condition is satisfied(e.g., determining whether a predetermined characteristic of the readdata or swap data is met (e.g., more ‘1’s than ‘0’s) or whether readdata or swap data exceeds (in any sense) the register-sourced comparevalue). Whichever data evaluation is performed, if the swap condition issatisfied, the read data may be returned to the swap-data source (e.g.,internal register or memory controller) with or without also writingback the read data to memory core 105 (e.g., if no data change willoccur, write-back may be suppressed or otherwise omitted) and,conversely, if a swap does occur (i.e., exchange-condition satisfied),the swap data may be returned to the swap-data source. Alternatively, oras part of a different conditional swap command, the read data may bereturned regardless of whether the exchange condition is satisfied.

Still referring to FIG. 1D, in a more general conditional operation, theread data may be conditionally modified according to an evaluation ofthe read data, externally sourced data and/or internally-sourced (e.g.,register-supplied) data, with the conditionally modified data writtenback to the memory core 105 and/or returned to the host requestor. Also,a combination of conditional modification and conditional swap may becarried out. As an example of a unary conditional operation, a read datavalue may be evaluated to determine whether it has more ‘0’ bits than‘1’ bits (or vice-versa) and, if so, complemented by the modify logic togenerate, as a modified data value, an inverted read data value that iswritten back to the memory core (and optionally transmitted back to theoperation requestor). As an example of a binary conditional operation,the read data value may be compared with an externally sourced datavalue, with the more superlative value (read data value or externallysourced value) modified in some way (e.g., incrementing a counter fieldwithin the more superlative value to indicate the number of comparisonsthe more superlative value has won) before writing the more superlativevalue back to the memory core 105. More generally, virtually any usefulconditional exchange and/or conditional modification may be executedwithin the modify logic 117 with optional return of the original,modified and/or superlative data to the memory core or to the memorycontroller.

FIG. 1E illustrates a special case of a modification operation in whichthe modified data is returned to the memory controller instead of theread data value. As discussed, the read data value may be absolutely(i.e., in all cases) modified or conditionally modified within themodify logic 117.

FIG. 1F illustrates another special case in which the read data is notreturned to the memory controller in either its original or modifiedform, while the data modified or conditionally modified by modify logic117 is written back to the memory core 105.

Reflecting on the atomic operations described in reference to FIGS.1B-1F, it can be seen that each generally involves bi-directional datatransfer with respect to the memory core 105 (including conditionalbi-directional transfer as the write-back may be conditionally omittedor suppressed as discussed above). Accordingly, such operations areoccasionally referred to herein as “duplex” operations to distinguishthem from “simplex” operations in which data flow is uni-directionalwith respect to the memory core. While such duplex operations may beimplemented with any underlying memory technology as discussed above, inmemory technologies that exhibit a relatively long write latency (e.g.,NAND-based flash memory, in which an entire physical page may be writtenat once), a number of implementation choices may be provided with regardto duplex operation timing. For example and without limitation, aninternal write cache may be provided to buffer data to be written aspart of a duplex operation, thereby enabling data write-back to becompleted quickly within the write-cache. Transfer from the write-cacheto the memory core may then occur over a longer time interval (e.g., asrequired by the underlying memory technology) and potentially at a latertime, after multiple updates to the contents of the write cache.

Examples of simplex operations, which are also supported by the atomicmemory device 103, include memory read operations and memory writeoperations as illustrated in FIGS. 1G and 1H. As shown, operation of themodify logic 117 is disabled (an/or the internal read-datapath/write-data path is decoupled from the modify logic 117 as indicatedby the ‘X’) so that read data flows uni-directionally from the memorycore 105 to the memory controller in a memory read operation (FIG. 1G)and write data flows uni-directionally from the memory controller to thememory core 105 in a memory write operation (FIG. 1H).

In the various embodiments described above, a memory device architecturesupporting atomic operations within the device input-output path mayreceive a superset of commands including both commands for atomicoperations as well as more traditional commands, such as those depictedwith reference to FIGS. 1G-1H.

FIG. 2 illustrates an embodiment of an atomic memory device 180 ingreater detail. As with the generalized atomic memory device of FIG. 1A,atomic memory device 180 includes a memory core 181, control logiccircuitry 183 and data I/O circuitry 185. For purposes of explanationonly, the memory core 105 is assumed to be a DRAM core having one ormore arrays of DRAM cells and corresponding sense amplifier banks 191that are accessed in response to row and column commands received viacommand path 214 and corresponding row and column addresses received viaaddress path 216 (the command and address paths collectively formingcommand/address path 210). Incoming memory access commands are receivedwithin a command decoder 197 (e.g., a state machine, sequencer or otherdecode-and-control circuitry) which issues corresponding control signalsto address decoding circuitry and to data I/O circuitry 185 to carry outthe requested operation. Upon receiving a row activation command (i.e.,command to transfer an address-selected row of data to the sense ampbank), for example, the command decoder 197 asserts a row-decode-enablesignal (“rowdec_en”) to row decoder 199 to enable the row decoder todecode a row address received via the address path 216 and therebyactivate a word line coupled to an address-selected row of cells withinthe memory core 181. The activated word line enables the contents of thecorresponding storage cells (i.e., the storage cells coupled to the wordline) to drive respective bit lines (or pairs of bit lines) which aresensed by the bank(s) of sense amplifiers 191. Through this “rowactivation” operation, the contents of a storage row may be sensed andlatched within the sense amplifier bank(s) 191, thus opening a “page” ofdata that may be accessed via column access (read and write) operations.Accordingly, upon receiving a column access command (i.e., command toread or write a column of data within a previously activated row, andthus a row of data within the sense amplifier bank), the command decoder197 issues a column-decode-enable signal (“coldec_en”) to enable thecolumn decoder 201 (or column multiplexer) to decode a column addressreceived via the address path 216 and, by that operation, form amultiplexed signal conduction path between an address-selected column ofdata within the sense amplifier bank(s) 191 and a parallel data pathreferred to herein as the core data path 260.

When an atomic command is received within the command decoder 197, thecommand decoder issues decode-enable signals in accordance with theatomic operation requested (e.g., column-decode-enable if column data isto be retrieved as part of the atomic operation) and also outputs anoperation-select (“opsel”) value to one or more modify logic circuits251 included within the data I/O circuitry 185. The command decoder 197may additionally output numerous signals and commands to control datasample timing (i.e., data reception), data transmission timing, databuffering, internal data transfer between component circuit blocks,specialized program/erase operation (e.g., in the case of NAND or NORflash or similar memory), maintenance operations (e.g., self-refresh,auto-refresh, signaling calibration, etc.) or any other control functionwithin the atomic memory device 181. Also, the command decoder 197 mayinclude or enable access to various status registers, control registersand data registers to allow device configurability. In one embodiment,for example, support for atomic operations may be disabled throughhost-instructed programming of a mode register 218 within the commanddecoder, thus enabling the atomic memory device to mimic the behavior oflegacy memory devices (i.e., in terms of operational timing and/ormanner of decoding incoming commands, etc.). As another example, one ormore operand registers 216 may be provided to provide operand(s) to thedata modify logic 251. In one implementation, for example, a solitaryprogrammable operand register 216 is used to provide operand data toeach of the modify logic circuits 251 within the data I/O circuitry 185.In an alternative embodiment, a bank of programmable operand registers216 are provided, with one or more of the operand registers 216 beingselected in accordance with an incoming atomic memory command to provideoperand data (“operand”) to the modify logic circuits 251. All such moderegisters 218 and operand registers 216 may be one-time or run-timeprogrammable. In the case of run-time programmable registers, forexample, the mode register 218 may be programmed in response to hostinstructions (e.g., provided via the memory controller) during systemstartup to establish an initial operating configuration, and the operandregister(s) 216 may be programmed during startup and as neededthereafter to provide operands for use in atomic operations. Valuesprogrammed within the mode registers 218 and operand registers 216 maybe transferred to the atomic memory device 180 via any or all of thesignal paths shown (address 216, command 214, data 212 (DQ)), or viaother signaling paths such as low-bandwidth control path, out-of-bandsignaling channel, etc.).

In one embodiment, the data I/O circuitry 185 includes a number of I/Obit-slice circuits 225 each coupled to a respective data link of theexternal data path via a pin (or pair of pins in a differentialsignaling implementation) or other integrated-circuit interconnect.Referring to the detail view of I/O bit-slice circuit 225 ₀ (“I/O slice225 ₀” for short), the on-chip portion of the incoming data link iscoupled to a signal transceiver formed by sampling circuit 231 andoutput driver 233. In one embodiment, data reception within the samplingcircuit 231 is timed by transitions of a receive timing signal (whichmay be a strobe signal or clock signal received in association with theincoming data signal, or an internally synthesized signal) so that thesampling circuit outputs a serial stream of received data bits ontowrite-data-in (“wdi”) line 232. As shown, the write-data-in line 232extends into the modify logic 251 where it is coupled to one or moremodify units 259 and also to a write-data-out (“wdo”) multiplexer 255(or other signal switching or selection logic). As discussed below, thewdo multiplexer 255 selects either the wdi line 232 or an output of themodify units 259 to drive a serial write-data-out line 234 (“wdo line”),and thus enables passage of write data to the memory core 181 in asimplex write operation, or passage of swap data or modified data to thememory core 181 in a duplex (atomic) operation.

In one embodiment, data to be written to the memory core 181 isconverted from serial to parallel form within each of the I/O bit-slices225, thus enabling the core cycle frequency (e.g., column-access cycletime (column cycle time), core clock cycle, or other cycle time of thememory core 181) to be a fraction of the data I/O frequency. That is, adeserializing circuit 241 (“deser”) is provided at the interface betweenthe core data path 260 and the data I/O circuitry 185 to convert serialdata conveyed on the wdo line 234 to parallel data for conveyance oncore data path 260 and storage within memory core 181. In the particularimplementation of FIG. 2 , for example, serial data on the wdo line 234is shifted bit by bit into deserializer 241 at the data I/O frequency(i.e., 1/(bit-time on data path)) and then framed and transferred out ofthe deserializer and onto core data path 260 at a word rate (e.g., theratio of serial data frequency to core frequency), e.g., ⅛^(th) or1/16^(th) the data I/O frequency. For example, after serial shifting ofeach group of sixteen bits into a shift register of deserializer 241,the core timing signal can be transitioned to transfer the 16-bit dataslice within the shift register, in parallel, onto core data path 260.In the exemplary embodiment of FIG. 2 , the atomic memory device 180 hasa 32-bit wide data interface (i.e., to interface to a 32-bit wideexternal data path) and enables operation of all the I/O bit slicecircuits 225 ₀-225 ₃₁ simultaneously (i.e., each circuit receives datain parallel) so that a core data word formed by a total of 32*16=512bits is transferred from the data I/O circuitry 185 to the core datapath 260 at the conclusion of each core framing interval (core cycle) asmarked by a transition of the core timing signal. The core data word isconveyed via the column decoder circuitry 201 to the appropriate 512 bitcolumn of sense amplifiers within sense amplifier bank(s) 191,overwriting the contents therein to complete a column write operation.Thereafter, after some number of memory write/read operations directedto the open page of data (i.e., contents of a storage row present in thesense amplifiers) is completed, a precharge operation may be carried outto close the open page. That is, if the page of data within the senseamplifier bank(s) 191 (which may include thousands or more 512-bitcolumns) has not already been written back to the corresponding row ofstorage cells, write-back to the storage cells is completed, thecorresponding word line deactivated, and the bit lines and senseamplifiers conditioned in preparation for the next row activationoperation.

Still referring to FIG. 2 , data flow in a simplex memory read operationis essentially the reverse of that described above in connection with asimplex memory write. That is, an address-selected column of data isoutput from the memory core 181 (i.e., from sense amplifier bank(s) 191in a DRAM embodiment) to the core data path 260 via the column decoder201. Serializers 243 (“ser”) within respective I/O bit slice circuits225 then operate in reverse-manner to the deserializers 241 describedabove, each converting a respective parallel set of 16 bits into acorresponding stream of sixteen serial bits that are output onto aread-data-in line 236 (the “rdi” line). The rdi line 236 is coupled tothe modify units 259 within the modify logic 251 and to a read-data-out(“rdo”) multiplexer 257. The rdo multiplexer 257 also receives a dataoutput from the modify units 259 and operates in response to a controlsignal to pass either the serial data stream supplied via the rdi line236 (i.e., the “retrieved data” or “read data”) or modified data fromthe modify units 259 to a read-data-out line 238 (the “rdo” line). Therdo line 238 conveys the serial stream of retrieved or modified data tooutput driver 233 which drives the data serially onto a respective oneof the signaling links of the external data path 212.

Still referring to FIG. 2 , the above-described relationship between thedata I/O frequency and core cycle interval is shown at 262 and 264. Thatis, during each core cycle interval in which data is being written intoand/or retrieved from the memory core 181, sixteen data bits aretransmitted serially via the wdo line 234 and/or the rdi line 236.During that same core cycle interval (though potentially offset toaccount for transfer delays within various circuits of the data I/Ocircuitry and/or core memory), a 512-bit core data word is transferredbetween the memory core and the core interface.

Reflecting on the atomic memory of FIG. 2 , it should be noted that thespecific numbers of bits, bit ratios, frequency ratios and so forth areprovided for purposes of example only. In all such cases, differentnumbers of bits and ratios may apply. Further, while specific circuitblocks have been shown, numerous other circuit blocks may also beprovided (and the functions of the circuit blocks shown and describedorganized differently with regard to such other circuit blocks) withoutdeparting from the scope of the present disclosure.

FIG. 3 illustrates an embodiment of a modify logic circuit 280 that maybe used to implement modify logic 251 of FIG. 2 . The modify logiccircuit 280 includes a modify controller 281, write-data-out (wdo) andread-data-out (rdo) multiplexers 285 and 287, and a set of one or moremodify units 293 ₀-293 _(N−1) (collectively, “293”). The modifycontroller 281 responds to incoming operation-select signals 128(“opsel”) by issuing multiplexer-control signals, wdo_sel and rdo_sel,to the wdo and rdo multiplexers 285 and 287, respectively, and byasserting enabling one or more modify-enable signals (en_0, en1, . . . ,enN−1) to enable corresponding modify units 293 to perform evaluationand/or modification operations. The modify controller 281 may alsoreceive one or more operation-result signals (res_0, res_1, res_N−1)from the modify units 293 and use those results in whole or part ingenerating the enable signals and multiplexer control signals. Forexample, in a compare-and-swap operation, one of the modify units 293may perform a data comparison and provide the comparison result to themodify controller 281 to enable determination of the wdo multiplexersetting (and/or rdo multiplexer setting). Although not specificallyshown, the modify controller 281 may be clocked or otherwise advancedbetween states in response to a clock signal (e.g., operating at thedata I/O frequency or a subdivided frequency thereof such as the coreclock cycle frequency) and may be implemented by any combination ofcombinatorial and state management logic. For example, in one embodimentthe modify controller 281 is implemented as a finite state machine,though an instruction sequencer or even purely combinatorialimplementation may be provided in alternative embodiments. In theseembodiments, the modify controller 281 may include sets of parallellogic, one for each slice (i.e., for each modify unit 293 ₀-293 _(N−1))for processing each slice in parallel.

Each of the modify units 293 or any subset thereof may be coupled to theread-data-in line 236 to enable receipt of retrieved serial data asnecessary to carry out the operation specified by opsel signal 128. Eachof the modify units 293 or a subset thereof may also be coupled to thewrite-data-in line 232 to enable receipt of externally received serialdata which may be write-data, swap data, an externally sourced operandor any other externally supplied information having useful applicationwithin the modify logic 280. The modify units 293 or any subset thereofmay be coupled to receive an operand from an operand register viaoperand path 141 as discussed above. Also, while a solitary operand path141 is shown, multiple operand paths may be provided to provide multipleoperands to a given modify unit 293 and/or to provide respectiveoperands to different modify units. Each of the modify units 293 or anysubset thereof may also include a select input (s0, s1, . . . , sN−1)coupled to receive a respective enable signal from the modify controller281, a result signal output (res_0, res 1, . . . , resN−1) to deliver anoperation-result signal to the modify controller 281, and aserial-data-output coupled to a modified-data line 284 to delivermodified data serially thereto. The modified-data line 284 conveysmodified data to the wdo multiplexer 285 to enable the modified data tobe written back to the memory core, and also to the rdo multiplexer 287to enable the modified data to be output from the atomic memory devicevia the external data path, both as discussed above.

Still referring to FIG. 3 , any number of modify units 293 may beprovided within modify logic 280, each to perform respective modifyfunctions or categories of modify functions. In the particularembodiment shown, modify units representative of three classes ofmodify-operations are depicted including a unary-operation unit 293 ₀, abinary-operation unit 293 ₁ and an evaluation-operation unit 293 _(N−1).

The unary-operation unit 293 ₀, demonstrates signal inputs and outputsrepresentative of those used to enable unary operations with respect todata retrieved from the memory core. That is, the rdi line 236 iscoupled to deliver the retrieved data to the unary operation unit which,when enabled by the modify controller 281 (i.e., en_0 asserted), carriesout a specified unary operation (or unary operation for which theunderlying circuitry is specifically designed) including for example andwithout limitation, increment/decrement, complement, absolute value,multiply or divide by fixed constant, exponent (raise to power), root(square root, cubed root or the like), logarithm, table lookup or anyother single-argument function. Any result, res_0, generated as part ofthe unary operation may be returned to the modify controller 281 and/orstored within the modify unit 293 ₀, or elsewhere within the atomicmemory device for later use. As an example, a carry bit (i.e., overflowbit) or borrow bit (i.e., underflow bit) may be generated as part of anincrement operation or decrement operation and summed with/subtractedfrom a subsequently retrieved data value to enable theincrement/decrement operation to be extended to data values greater than16 bits (i.e., enabling multiple retrieved data values to be processedas constituent parts of a larger data value).

The binary-operation unit 293 ₁ demonstrates signal inputs and outputsrepresentative of those used to enable binary operations with respect todata retrieved from the memory core. In the particular implementationshown, the binary-operation unit receives the retrieved data via rdiline 236 and an operand supplied via wdi line 232 as inputs. Asdiscussed above, an operand may additionally or alternatively besupplied via from one or more operand registers within the atomic memorydevice via respective operand paths 141. In any case, the binaryoperation unit 293 ₁ carries out a binary operation (or ternaryoperation, quaternary operation, etc. according to the number ofsupplied operands) when enabled by the modify controller 281 and outputsresultant modified data onto the modified-data line 284 and, optionally,a result signal (e.g., borrow, carry, etc.) onto the result signal line,res_1. As with the unary-operation unit 293 ₀, the binary-operation unit293 ₁ may execute a selected, specified operation (e.g., specified bythe modify controller) or an operation for which the underlyingcircuitry is specifically designed. Examples of the binary operationsperformed include, for example and without limitation, arithmeticoperations (add, subtract, multiply, divide), bit-wise logicaloperations (e.g., a mask operation), Boolean operations (AND, OR, XOR, .. . ), two-dimensional table lookup, or any other multi-operandfunctions.

Still referring to FIG. 3 , the evaluation-operation unit 293 _(N−1) maybe viewed as a form of unary or binary operation unit (according to thenumber of operands delivered) but is presented separately to emphasizethat at least some operations do not require data output onto themodified-data line 284 (hence the dashed interconnection of unit 293_(N−1) and modified-data line 284). That is, in one embodiment, theevaluation-operation unit performs an evaluation of a retrieved datavalue alone (unary evaluation) or in combination with data received froman external source and/or one or more operands (binary evaluation) andoutputs an evaluation-result signal on result line res_N−1 and/or anevaluation data value (e.g., comparison winner) on modified-data line284. The result of the evaluation may be signaled to the modifycontroller 281, for example, to enable the modify controller 281 toresponsively control the wdo and/or rdo multiplexers 285, 287. As anexample, if an evaluation result resolves to “TRUE” (as signaled viares_N−1), then the wdi line 232 can be used to drive wdo line 234,thereby enabling a data swap. Otherwise, if the evaluation resultresolves to “FALSE”, a write-back operation can be enabled, for example,by passing the retrieved data through the evaluation-operation unit 293_(N−1) to the modified-data line 284 (e.g., as a comparison winner), andsetting the wdo multiplexer 285 to couple the modified-data line 284 tothe wdo line 234, thereby routing the retrieved data onto the wdo line234 for write-back to the memory core. An example of the foregoingoperation is an operation to swap data only if the incoming value isgreater than the resident value in memory.

As an example of a unary evaluation, retrieved data may be evaluated todetermine whether a particular Boolean condition is met (e.g., retrievedvalue evaluates to TRUE or FALSE) or whether the retrieved dataotherwise meets a predetermined condition, with data exchange or othermodify operations being performed with respect to the same retrieveddata value or a subsequently retrieved data value according to theevaluation result. For example, one conditional-increment function mayincrement data only if not at a maximum (e.g., either a defined maximumof data or an increment that avoids an overflow). In a binaryevaluation, the retrieved data value may be compared with the incomingoperand data (i.e., from register and/or external source) to generate anoperation result (e.g., inequality, match, logical combination ofretrieved value and operand satisfy a predetermined orregister-specified condition, etc.), with the operation result againbeing used to enable conditional data exchange or other modifyoperations with respect to the retrieved data value or a subsequentlyretrieved data value.

As shown in detail view 301, each of the modify units 293 may beimplemented by a modify circuit 305 and one or more delay circuits, 307,309, 311. The modify circuit 305 may include any combinatorial orstate-based logic for generating an operation result and modified datain response to an enable signal (which may be a multi-bit signal toinstruct operation of one of multiple possible operations supported bythe modify circuit 305). In general, such logic may be synthesized usingcircuit design tools by specifying the operation to be performed (andthus the operation result and the modified data output) with respect tothe incoming retrieved data and any operands. The delay circuits 307,309, 311 may include hardwired or adjustable delay circuits (e.g., inresponse to a register-programmed value, or a dynamic value provide inconnection with the operation-selection value) to delay propagation ofany or all incoming operands (ingress delay circuits 307, 309) to theinputs of the modify circuit 305, and/or to delay propagation of themodified data to the modified-data line 284 (egress delay circuit 311)and/or to delay output of the operation result (result delay circuit313) to the modify controller. By this arrangement, incoming operandsmay be provided to the modify circuit 305 at an appropriate time or themodified data or an operation-result may be driven at a desired time,thus enabling coordination of various events within and external to themodify logic 280 as well as pipelining of atomic operations. A designermay utilize these features so as to tailor (e.g., optimize) traffic flowthrough the input-output path of the memory device for the atomicoperations supported for the particular design.

FIG. 4 illustrates a table of operations (340) that may be initiated andcontrolled by the modify controller of FIG. 3 in accordance with theoperation specified by the command decoder or other control circuitrywithin the atomic memory device. Starting with simplex memory read andsimplex memory write operations shown in the first two rows of table340, because no data is being conditionally or absolutely transmitted ina direction counter to the simplex data flow, no modify unit is enabled.Instead, the modify controller sets the rdo multiplexer to forward theretrieved data (“read data”) onto the read-data-out line in a simplexmemory read operation, and sets the rdi multiplexer to forward theincoming write data onto the write-data-out line in a simplex memorywrite operation. Although only two simplex data operations are shown,other simplex operations may be performed, including masked write,masked read, etc.

Turning to the duplex (atomic) operations listed in table 340, in aread/increment operation, the modify controller enables a unary modifyunit to carry out an increment operation with respect to data retrievedfrom the memory core (the “read data), and sets the rdo and wdomultiplexers to output the read data from the atomic memory device andto deliver the modified data output from the enabled modify unit (i.e.,the incremented read data in this example) to the memory core to bestored in place of the just-retrieved read data. Thus, a memory read isperformed concurrently with incrementing the read data value, returningthe read data to the host requestor concurrently (i.e., at least partlyoverlapping in time) with writing the incremented read data back to thememory core. The increment/read operation is similar (i.e., unary modifyunit also selected), except that the modified (incremented) data is bothwritten back to the memory core and returned to the host requester.

Other examples of unary operations specifically shown in table 340include read/complement (read a data value and overwrite it with itscomplement (inverted data value)) and complement/read (overwrite theread data value with its complement and return the complement value tothe host). In all such cases, the write-back to the memory core may beconditioned on evaluation of the retrieved data and/or one or moreoperands. A 1's complement operation may also be used (as opposed to astraight complement). As should be apparent, although not specificallylisted in table 340, numerous other unary operations may be performed asdiscussed above.

Turning to examples of binary duplex operations that referenceregister-sourced operands, in a read/add-offset operation, the offsetvalue within a register is added to a retrieved data value to establisha variable+constant result that may be unconditionally or conditionallywritten back to the memory core. More specifically, a binary-operationunit that performs the data+operand operation is enabled by the modifycontroller, and the rdo and wdo multiplexers are set to pass theretrieved data value to the rdo line and the modified data value to thewdo line, respectively. In an add-offset/read operation, similar resultsare obtained, but the modified data value (retrieved data value plusoperand) is returned to the host requestor instead of the read datavalue. Read/subtract-offset and subtract-offset/read operations arepresented as additional examples of binary, register-based operations.Though not specifically listed in table 340, numerous otherregister-based binary operations may be performed.

The last set of exemplary operations presented in table 340 are binaryoperations that involve a host-supplied operand, that is, binary duplexoperations in which an externally-sourced operand delivered via the wdiline is supplied to a modify unit together with a retrieved data value.The specific examples presented include swap, compare-and-swap,read/add-variable, and add-variable/read. In the swap operation, nomodify unit need be enabled (as signified by the “N/A” or not-applicabledesignation) and instead the modify controller sets the rdo and wdomultiplexers to output the read data to the host requestor and todeliver the swap data to the memory core to overwrite the just-retrievedread data (thus effecting a swap operation). A compare-and-swapoperation is carried out similarly, except that the modify controllerenables a compare operation within an evaluation-operation unit, andthen sets the rdo and wdo multiplexers in accordance with the compareresult. In the embodiment shown, for example, the wdo multiplexer maydeliver either the swap data or read data onto the wdo line(alternatively, no data may be driven onto the wdo line if the swap datais not to be written back to the memory core) and conversely delivereither the read data or the swap data onto the rdo line according to thecomparison result. That is, if a swap is to be executed, the swap datais delivered to the memory core and the read data is returned to thehost requestor. If a swap is not to be executed, the read data isdelivered to the memory core (or no write back is executed) and the swapdata is optionally returned to the memory requestor to enable the memoryrequestor to ascertain the comparison result.

Turning to the read/add-variable operation, retrieved data is returnedto the host requestor and also added to an externally-supplied operandto generate a sum that is written back, as a modified data value, to thememory core. In the case of an add-variable/read operation, the sum isboth written back to the memory core and returned to the host requestor.Again, though not specifically listed in table 340, numerous otherbinary operations that involve host-supplied operands may be performed.Also, as described above, all such arithmetic operations, regardless oftheir operand source, may be extended to enable operation with respectto multiple retrieved data values through borrow or carry storage orother state information as appropriate for the operation performed.

FIG. 5 illustrates a generalized and exemplary operation of an atomicmemory device in response to receipt of a memory access command as shownat 351. If no memory read is required (determined in decision block353), then the requested memory access is a simplex write. Accordingly,the incoming write data value is stored in the memory core as shown at355. If a memory read is required, then read data is retrieved from thememory core in an operation shown generally at 357. If the memory accesscommand indicates a duplex operation (i.e., data flowing both into andout of the memory core in response to the memory access command), thenexecution proceeds to decision block 359. Otherwise, the memory accesscommand is simplex read command, and the read-data-out multiplexer isset to select the read-data-in line and thus output the read data to thehost requestor as shown at 361, thereby completing the simplexoperation.

Continuing with the case of a duplex operation (i.e., affirmativedetermination at block 359), if the atomic command indicates a binaryoperation (i.e., it is determined at 363 that the operation involves adata source other than the retrieved data value), then the operand isreceived from a register or external source (e.g., from an operandregister or via the write-data-in line) at 365 and supplied to theappropriate modify unit. Thereafter, whether unary operation (negativedetermination at decision block 363) or binary operation, theappropriate modify unit is selected in accordance with the specifiedatomic operation and enabled at 367 to generate a modified data value orevaluation result with respect to the retrieved data and any suppliedoperands. The read-data-out multiplexer and write-data-out multiplexerare set at 369 in accordance with the duplex operation being performedand any evaluation result, thus enabling concurrent output of the readdata or modified data to the host requestor at 371 and/or storage ofoperand data (e.g., swap data) or modified data in the memory core at373.

FIG. 6 is a timing diagram illustrating signal timing during anexemplary duplex operation within the atomic memory device of FIG. 3 .At the start of a core cycle ‘i,’ a memory access command 385 specifyinga duplex (atomic) operation is received via the command/address path 210(C/A) concurrently with receipt of an operand 386 to be applied withinthe duplex operation via the external data path 212 (D/Q). After a datasampling delay, the operand is presented on the write-data-in line 232as shown at 388 and thus to the modify logic of the atomic memorydevice. Meanwhile, during the interval marked in FIG. 6 as “Read DataRetrieval,” read data is retrieved from the memory core in accordancewith an address provided in association with the duplex operation,eventually becoming valid and presented to the modify logic on theread-data-in line 236 as shown at 390. Assuming a duplex operation inwhich read data or modified data (including swap data) is to be returnedto the host requestor, the output of the modify logic (read data ormodified data or swap data, for example) is output onto theread-data-out line 238 as shown at 392 and, at approximately the sametime (or shortly before or after data output onto rdo line 238),modified data (including swap data) is output onto the write-data-outline to 234 be written back to the memory core as shown at 394.Concurrently with write-back to the memory core, data output onto theread-data-out line is driven onto the external data path 212 as shown at396 and thereby returned to the host requestor during the beginning ofthe succeeding core cycle (i.e., core cycle i+1). In the particularexample shown, a simplex memory read operation is commanded at the startof core cycle i+1 (i.e., as shown at 398), with the data retrievaloperation being carried out with essentially the same timing as the dataretrieval in the preceding duplex operation. That is, read data i+1becomes available on the rdi line as shown at 400 (i.e., after the ReadData Retrieval interval), and is routed onto the rdo line shortlythereafter as shown at 402. Read data i+1 is then output onto theexternal data path as shown at 404, thus completing the simplex memoryread just as another read operation is received in the ensuing corecycle.

It should be noted that the various circuits disclosed herein may bedescribed using computer aided design tools and expressed (orrepresented), as data and/or instructions embodied in variouscomputer-readable media, in terms of their behavioral, registertransfer, logic component, transistor, layout geometries, and/or othercharacteristics. Formats of files and other objects in which suchcircuit expressions may be implemented include, but are not limited to,formats supporting behavioral languages such as C, Verilog, and VHDL,formats supporting register level description languages like RTL, andformats supporting geometry description languages such as GDSII, GDSIII,GDSIV, CIF, MEBES and any other suitable formats and languages.Computer-readable media in which such formatted data and/or instructionsmay be embodied include, but are not limited to, computer storage mediain various forms (e.g., optical, magnetic or semiconductor storagemedia, whether independently distributed in that manner, or stored “insitu” in an operating system).

When received within a computer system via one or more computer-readablemedia, such data and/or instruction-based expressions of the abovedescribed circuits may be processed by a processing entity (e.g., one ormore processors) within the computer system in conjunction withexecution of one or more other computer programs including, withoutlimitation, net-list generation programs, place and route programs andthe like, to generate a representation or image of a physicalmanifestation of such circuits. Such representation or image maythereafter be used in device fabrication, for example, by enablinggeneration of one or more masks that are used to form various componentsof the circuits in a device fabrication process.

In the foregoing description and in the accompanying drawings, specificterminology and drawing symbols have been set forth to provide athorough understanding of the present invention. In some instances, theterminology and symbols may imply specific details that are not requiredto practice the invention. For example, any of the specific numbers ofbits, signal path widths, signaling or operating frequencies, componentcircuits or devices and the like may be different from those describedabove in alternative embodiments. In other instances, well-knowncircuits and devices are shown in block diagram form to avoid obscuringthe present invention unnecessarily. Additionally, the interconnectionbetween circuit elements or blocks may be shown as buses or as singlesignal lines. Each of the buses may alternatively be a single signalline, and each of the single signal lines may alternatively be buses.Signals and signaling paths shown or described as being single-ended mayalso be differential, and vice-versa. A signal driving circuit is saidto “output” a signal to a signal receiving circuit when the signaldriving circuit asserts (or deasserts, if explicitly stated or indicatedby context) the signal on a signal line coupled between the signaldriving and signal receiving circuits. The expression “timing signal” isused herein to refer to a signal that controls the timing of one or moreactions within an integrated circuit device and includes clock signals,strobe signals and the like. “Clock signal” is used herein to refer to aperiodic timing signal used to coordinate actions between circuits onone or more integrated circuit devices. “Strobe signal” is used hereinto refer to a timing signal that transitions to mark the presence ofdata at the input to a device or circuit being strobed and thus that mayexhibit periodicity during a burst data transmission, but otherwise(except for transition away from a parked condition or other limitedpre-amble or post-amble transition) remains in a steady-state in theabsence of data transmission. The term “coupled” is used herein toexpress a direct connection as well as a connection through one or moreintervening circuits or structures. Integrated circuit device“programming” may include, for example and without limitation, loading acontrol value into a register or other storage circuit within the devicein response to a host instruction and thus controlling an operationalaspect of the device, establishing a device configuration or controllingan operational aspect of the device through a one-time programmingoperation (e.g., blowing fuses within a configuration circuit duringdevice production), and/or connecting one or more selected pins or othercontact structures of the device to reference voltage lines (alsoreferred to as strapping) to establish a particular device configurationor operation aspect of the device. The terms “exemplary” and“embodiment” are used to express an example, not a preference orrequirement.

While the invention has been described with reference to specificembodiments thereof, it will be evident that various modifications andchanges may be made thereto without departing from the broader spiritand scope. For example, features or aspects of any of the embodimentsmay be applied, at least where practicable, in combination with anyother of the embodiments or in place of counterpart features or aspectsthereof. Accordingly, the specification and drawings are to be regardedin an illustrative rather than a restrictive sense.

What is claimed is:
 1. A dynamic random access memory (DRAM) devicecomprising: a memory core having an array of DRAM cells; a register tostore first data in response to a register-write command; acommand/address interface that receives commands and addresses, thecommand/address interface to receive the register-write command and thefirst data, and then, after the first data has been stored in theregister, to receive first and second memory access commands; a datainterface to receive second data in response to the second memory accesscommand, wherein the data interface does not receive the first data; andcontrol circuitry to write the first data from the register to thememory core in response to the first memory access command and to writethe second data from the data interface to the memory core in responseto the second memory access command.
 2. The DRAM device of claim 1wherein the control circuitry comprises circuitry, responsive to thefirst memory access command, to convey the first data from the registerto the memory core and enable storage of the first data within thememory core, and wherein the circuitry to write the second data from thedata interface to the memory core in response to the second memoryaccess command comprises circuitry, responsive to the second memoryaccess command, to convey the second data from the data interface to thememory core and enable storage of the second data within the memorycore.
 3. The DRAM device of claim 1 wherein the memory core comprises asense amplifier bank coupled to the array of DRAM cells, and wherein thecontrol circuitry comprises circuitry to write the first data from theregister into the sense amplifier bank in response to the first memoryaccess command and to write the second data from the data interface intothe sense amplifier bank in response to the second memory accesscommand.
 4. The DRAM device of claim 1 wherein the command/addressinterface is to receive a first address value with the first memoryaccess command and receive a second address value with the second memoryaddress command, and wherein the control circuitry comprises circuitryto write the first data from the register to the memory core at one ormore storage locations indicated by the first address value and to writethe second data from the data interface to the memory core at one ormore storage locations indicated by the second address value.
 5. TheDRAM device of claim 1 wherein the data interface comprises circuitry toreceive the second data at a predetermined time relative to reception ofthe second memory access command.
 6. The DRAM device of claim 1 whereinthe data interface comprises data inputs to be coupled to external datasignaling lines, one or more timing signal inputs to be coupled to oneor more external timing signal lines, and sampling circuitry to sampledata signals, arriving at the data inputs, at times indicated by a datastrobe signal arriving at the one or more timing signal inputs.
 7. TheDRAM device of claim 1 wherein the control circuitry to write the firstdata from the register to the memory core comprises circuitry,responsive to the first memory access command, to read third data fromthe memory core, write the first data into the memory core in place ofthe third data, and output the third data from the DRAM device via thedata interface.
 8. The DRAM device of claim 7 wherein the first memoryaccess command comprises a swap instruction and a first address value,and wherein the circuitry to read the third data from the memory coreand write the first data into the memory core in place of the third datacomprises circuitry, responsive to the swap instruction, to read thethird data from one or more locations within the memory core indicatedby the first address value and to write the first data into the one ormore locations within the memory core such that the third data isoverwritten by the first data within the memory core.
 9. The DRAM deviceof claim 1 wherein the circuitry to store the first data within theregister in response to the register-write command comprises circuitryto store N constituent data bits of the first data, where N is aninteger greater than one.
 10. The DRAM device of claim 9 wherein thedata interface comprises an N-bit wide data interface to be coupled to Ndata signaling links external to the DRAM device.
 11. The DRAM device ofclaim 1 wherein the first and second memory access commands specifydifferent types of memory access operations, wherein the first memoryaccess command is an atomic write command and the second memory accesscommand is a simplex write atomic command.
 12. A method of operationwithin a memory device having a dynamic random access memory (DRAM) coreand a command/address interface to receive commands and addresses, themethod comprising: receiving, via the command/address interface, aregister write command and first data; storing the first data within aprogrammable register in response to the register write command;receiving, via the command/address interface after storage of the firstdata within the programmable register, a first memory access command;writing the first data from the programmable register to the DRAM corein response to the first memory access command; receiving a secondmemory access command via the command/address interface; receivingsecond data via a data interface in response to the second memory accesscommand; and writing the second data from the data interface to the DRAMcore in response to the second memory access command.
 13. The method ofclaim 12 wherein writing the first data from the programmable registerto the DRAM core comprises conveying the first data from theprogrammable register to the DRAM core in response to the first memoryaccess command and storing the first data within the DRAM core inresponse to the first memory access command, and wherein writing thesecond data from the data interface to the DRAM core comprises conveyingthe second data from the data interface to the DRAM core in response tothe second memory access command and storing the second data within theDRAM core in response to the second memory access command.
 14. Themethod of claim 12 wherein: writing the first data to the DRAM corecomprises writing the first data from the programmable register into asense amplifier bank within the DRAM core in response to the firstmemory access command; and writing the second data to the DRAM corecomprises writing the second data from the data interface into the senseamplifier bank in response to the second memory access command.
 15. Themethod of claim 12 wherein receiving the second data via the datainterface comprises circuitry receiving the second data via the datainterface at a predetermined time relative to reception of the secondmemory access command.
 16. The method of claim 12 further comprisingreceiving a data strobe signal via the data interface and whereinreceiving the second data via the data interface comprises sampling datasignals at respective data inputs of the data interface at timesindicated by the data strobe signal.
 17. The method of claim 12 furthercomprising reading third data from the memory core in response to thefirst memory access command and outputting the third data from the DRAMdevice via the data interface, and wherein writing the first data fromthe programmable register to the memory core in response to the firstmemory access command comprises writing the first data to the memorycore in place of the third data.
 18. The method of claim 17 whereinreceiving the first memory access command comprises receiving a swapinstruction and a first address value, and wherein reading the thirddata from the memory core comprises, in response to the swapinstruction, reading the third data from one or more locations withinthe memory core indicated by the first address value and then writingthe first data into the memory core at the one or more locations suchthat the third data is overwritten by the first data within the memorycore.
 19. The method of claim 12 wherein storing the first data withinthe programmable register comprises storing N constituent data bits ofthe first data, N being an integer greater than one, and whereinreceiving the second data via the data interface comprises receiving thesecond data via an N-bit data interface.
 20. A dynamic random accessmemory (DRAM) device comprising: a memory core having an array of DRAMcells and a sense amplifier bank coupled to the array of DRAM cells; afirst interface to receive a register-write command and first data, andto receive first and second command/address values after receiving theregister-write command and first data, the first command/address valueincluding both a first column access command and a first column address,and the second command/address value including both a second columnaccess command and a second column address; a programmable register tostore first data in response to the register-write command; a datainterface having (i) a timing signal input to receive a data strobesignal and (ii) data signal inputs to receive second data synchronouslywith respect to the data strobe signal starting at a predetermined timerelative to reception of the second memory access command; and memoryaccess circuitry that: responds to the first column access command bywriting the first data from the programmable register to a first columnof storage elements within the sense amplifier bank indicated by thefirst column address, and responds to the second memory access commandby writing the second data from the data interface to a second column ofstorage elements within the sense amplifier bank indicated by the secondcolumn address.